The present invention relates to methods for packaging integrated circuits. More specifically, but without limitation thereto, the present invention relates to a method for increasing the number of traces of a ball grid array integrated circuit package.
A typical ball grid array limits the number of I/O traces to a ball grid of four rows. As circuits evolve with increasing complexity, higher ball counts are needed. A problem with the current limitation of four rows is that the standard design parameters of trace width, trace spacing, via diameter, and I/O pad diameter would have to be changed to accommodate a higher number of traces.
The present invention advantageously addresses the problems above as well as other problems by providing a method for increasing the number of traces for a ball grid array package without changing the standard design parameters.
In one embodiment, the present invention may be characterized as a method of making a ball grid array package that includes the steps of (a) laying out an even I/O pad row and an odd I/O pad row of m I/O pads each for a ball grid array package wherein m is a positive integer, (b) laying out an even via row of m+1 vias directly below each odd I/O pad row, and (c) laying out an odd via row of mxe2x88x921 vias directly below each even I/O pad row.
In another embodiment, the present invention may be charcterized as a ball grid array package that includes an even I/O pad row and an odd I/O pad row of m I/O pads each wherein m is a positive integer, an even via row of m+1 vias directly below each odd I/O pad row, and an odd via row of mxe2x88x921 vias directly below each even I/O pad row.